Deaths of marathoners are extremely rare

When word circulates that a runner has died of a heart attack, as the inexhaustible ultramarathoner Micah True did last month during a solo wilderness trail run, many people begin to wonder about the healthiness of prolonged strenuous activity.

Could marathon training and racing have damaged the heart muscle of True, 58, a lead character in the book "Born to Run"? And, conversely, shouldn't marathon training have made him — and, by extension, all runners — immune to heart disease?

Thousands of runners and walkers cross the John Ringling Causeway bridge during the First Watch Sarasota Half Marathon and Relay on March 11. (Staff photo by Dan Wagner)

Those questions, familiar to any scientist or physician who works with endurance athletes, inspired several recently published studies of the relative risks of marathon running. The science suggests that, overall, distance running and racing are extremely unlikely to kill you — except when, in rare instances, they do.

The newest of the studies, published in The American Journal of Sports Medicine, gathered publicly available data on participation in and deaths during or immediately after every known marathon race in the United States from 2000 to 2009.

The totals were, of necessity, approximate.

"Marathon-related deaths are not reportable," said Dr. Julius Cuong Pham, an associate professor of emergency medicine at Johns Hopkins University School of Medicine and lead author of the study.

Doctors aren't required by law to report information about deaths during marathons to the local health authorities.

So the Johns Hopkins researchers turned to news reports, which are actually a very reliable guide to such fatalities.

"It's sensational news when someone dies during a marathon," Pham said. "It makes headlines," and the coverage skews public opinions about the safety of the event. "Tens of thousands of people finish a marathon, but people hear mostly about the one who dies," he said.

"We did not set out to in any way minimize the tragedy of a single death," he said. "But we did want to determine what the record really shows."

What the researchers found was that, even as participation in marathon racing almost doubled during the past decade, to more than 473,000 finishers in 2009 from about 299,000 in 2000, the death rate remained unchanged, and vanishingly small. A total of 28 people died during or in the 24 hours immediately after a marathon, most of them men, and primarily from heart problems. (A few of the deaths were due to hyponatremia, or low blood sodium, in those who drank excessive amounts of fluid.) Those numbers translate into less than one death per 100,000 racers.

"Our data shows, quite strongly, that marathon running is safe for the vast majority of runners," Pham said, "and I suspect that, for many of the runners," the activity saved them from suffering a heart attack that might otherwise have been brought on by a sedentary, unhealthy lifestyle.

A similar epidemiological study, published in January in The New England Journal of Medicine, reached the same conclusion as Pham's report, even as its authors looked more widely at data involving fatal and nonfatal cardiac arrests in half and full marathons over the past decade. The researchers found 59 cases of cardiac arrest during a half or full marathon, 51 of them in men, and 42 of them fatal. The average age of the affected racers was 42, and an overwhelming majority of them were approaching the finish line — within the last six miles for the marathon and the final three for the half — when they fell.

"The findings reinforce what we really already knew," said Dr. Paul Thompson, the chief of cardiology at Hartford Hospital in Connecticut, an author of the study and a longtime marathon runner, "which is that you are at slightly higher risk of suffering a heart attack during a marathon" than if you were merely sitting or walking sedately during those same hours.

"But overall, running decreases the risk of heart disease" and therefore the likelihood of your suffering cardiac arrest at all.

"Genetics, viruses, bad habits from the past, bad diet or plain bad luck" can contribute to the development of plaques within the arteries or of heart damage like cardiomyopathy, an unnatural enlargement of the heart muscle, which running simply cannot prevent.

True was found during an autopsy to have suffered from cardiomyopathy, the origins of which are unknown, according to a medical examiner in New Mexico, where True died.

If you have any symptoms of heart problems, like chest pain, dizziness or unusual fatigue, you should, obviously, see a doctor, no matter how fit you believe yourself to be, Pham said.

Last modified: June 4, 2012
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